Electrowetting display pixels with pixel walls having non-planar side surfaces

Abstract

An electrowetting display device includes a first support plate and a second support plate. A first fluid and a second fluid that is immiscible with the first fluid are between the first support plate and the second support plate. A plurality of pixel walls having concave side surfaces are formed on the first support plate to define a plurality of electrowetting pixels. A pixel electrode is disposed on the first support plate for applying a voltage within each electrowetting pixel to cause relative displacement of the first fluid and the second fluid.

What is claimed is: 
     
       1. An electrowetting display device, comprising:
 a first support plate and a second support plate; 
 a first fluid and a second fluid that is immiscible with the first fluid, the first fluid and the second fluid between the first support plate and the second support plate; 
 a plurality of pixel walls formed on the first support plate, each pixel wall in the plurality of pixel walls having first and second side surfaces, each of the first and second side surfaces of each pixel wall in the plurality of pixel walls being concave and curvilinear, the plurality of pixel walls being associated with a plurality of electrowetting pixels; and 
 a pixel electrode disposed on the first support plate for applying a voltage within each electrowetting pixel of the plurality of electrowetting pixels to cause relative displacement of the first fluid and the second fluid, wherein at least partly in response to the voltage being applied to the pixel electrode, a portion of the first fluid or the second fluid forms a droplet against the first or second side surface of one of the plurality of pixel walls. 
 
     
     
       2. The electrowetting display device of  claim 1 , wherein each of the first and second side surfaces of each pixel wall in the plurality of pixel walls is concave with respect to a plane extending through the pixel wall perpendicular to a top surface of the first support plate. 
     
     
       3. The electrowetting display device of  claim 1 , wherein each of the first and second side surfaces of each pixel wall in the plurality of pixel walls is substantially symmetrical about a plane extending along a length of the pixel wall perpendicular to a top surface of the first support plate. 
     
     
       4. A display device, comprising:
 a first support plate having a top surface; and 
 a wall on the first support plate, the wall having an end surface and a midpoint between the end surface and the top surface, the wall having a first width at the end surface and a second width less than the first width at the midpoint, a portion of the wall associated with an electrowetting pixel, a first side surface of the portion of the wall facing the electrowetting pixel being at least partially concave, wherein a first fluid disposed within the electrowetting pixel contacts the first side surface. 
 
     
     
       5. The display device of  claim 4 , wherein the electrowetting pixel comprises a pixel electrode disposed on the first support plate for applying a voltage within the electrowetting pixel to cause relative displacement of the first fluid and a second fluid disposed within the electrowetting pixel. 
     
     
       6. The display device of  claim 5 , further comprising a second wall on the first support plate, the second wall associated with the electrowetting pixel and having planar side surfaces, wherein at least partly in response to the voltage being applied to pixel electrode, a portion of the first fluid or the second fluid moves towards the first side surface of the portion of the wall and away from the second wall. 
     
     
       7. The display device of  claim 4 , wherein the first side surface includes a planar surface, the planar surface being perpendicular to the first support plate. 
     
     
       8. The display device of  claim 7 , wherein the planar surface extends from a top of the first side surface to a midpoint of the first side surface between the top of the first side surface and the top surface of the first support plate. 
     
     
       9. The display device of  claim 7 , wherein the planar surface extends from the top surface of the first support plate to a midpoint of the first side surface between a top of the first side surface and the top surface of the first support plate. 
     
     
       10. The display device of  claim 4 , wherein the portion of the wall further comprises a second side surface opposing the first side surface, wherein the second side surface is associated with an additional pixel and is at least partially concave. 
     
     
       11. The display device of  claim 4 , wherein the first side surface is concave with respect to a plane extending through the wall and perpendicular to the top surface of the first support plate. 
     
     
       12. The display device of  claim 4 , wherein the portion of the wall further comprises a second side surface of the portion of the wall opposing the first side surface and the first side surface of the portion of the wall and the second side surface of the portion of the wall are substantially symmetrical about a plane oriented along a length of the wall perpendicular to the first support plate. 
     
     
       13. The display device of  claim 4 , further comprising a second support plate parallel to the first support plate, the second support plate including a spacer protruding from the second support plate toward the end surface of the wall. 
     
     
       14. The display device of  claim 13 , wherein the spacer is in contact with the end surface of the wall. 
     
     
       15. The display device of  claim 4 , wherein the first width is between about 2 micrometers and about 6 micrometers. 
     
     
       16. The display device of  claim 15 , wherein the second width is between about 1 micrometer and about 2 micrometers, and a height of the wall is between about 2 micrometers and about 6 micrometers. 
     
     
       17. A method for fabricating at least a portion of an electrowetting display device, the method comprising:
 depositing a photoresist over a surface of a support plate; 
 positioning a diffractive mask over the support plate, the diffractive mask including a pattern of non-transparent material configured to disperse light passing through the diffractive mask; and 
 patterning the photoresist through the diffractive mask to cure a portion of the photoresist into a pixel wall having a concave side surface. 
 
     
     
       18. The method of  claim 17 , further comprising:
 depositing a second photoresist over the support plate; and 
 patterning the second photoresist to form at least a portion of the pixel wall with a reflective surface positioned underneath the support plate. 
 
     
     
       19. The method of  claim 17 , wherein patterning the photoresist comprises patterning the photoresist to form a plurality of pixel walls associated with individual electrowetting pixels. 
     
     
       20. The method of  claim 17 , further comprising mounting a second support plate parallel to the support plate, the second support plate including a spacer protruding from the second support plate toward a top surface of the wall. 
     
     
       21. The method of  claim 20 , wherein mounting the second support plate comprises positioning the spacer in contact with the top surface of the pixel wall. 
     
     
       22. A display device, comprising:
 a first support plate having a first surface; and 
 a wall on the first surface, the wall having a first width at a top surface of the wall and a second width less than the first width at a point between the top surface and the first surface, a portion of the wall associated with an electrowetting pixel, a first side surface of the portion of the wall facing the electrowetting pixel being at least partially concave, wherein a first fluid disposed within the electrowetting pixel contacts the first side surface.